Short-Pulse, High-Speed Laser Platform for Temperature Measurements and Chemical Species Imaging at 100 kHz for Combustor/Augmentor Stability

AEDC has determined that there is a need exist to develop non-intrusive, high-data-acquisition-rate, multi-parameter measurement techniques and tools for characterization of the thermodynamic properties of the APTU (Aerodynamic and Propulsion Test Unit) facility flow. This includes temperature and species concentrations of the flow impinging or entering the test article. Also, high-speed measurements during transient phenomena such as screech and rumble are needed. The proposed burst-mode laser platform will provide high-repetition-rate, high energy/intensity pulses and enable real-time coherent ant-Stokes Raman scattering (CARS)-based temperature measurements as well as chemical species imaging in high-speed subsonic or hypersonic flows at 100 kHz rate or greater to enable detailed understanding, accurate prediction, and a priori mitigation of combustion instabilities in transformational aircraft propulsion systems. The proposed laser platform will increase temporally resolved temperature and critical species measurement speed by four orders-of-magnitude (10,000 times) as compared to the current state-of-the-art 10-Hz CARS diagnostic technology. This will allow for the first time, high fidelity real-time temperature measurements in hypersonic and turbulent combustion flow facilities. This effort will also enable validation of 3D temperature dependent transient predictive models of combustion instabilities.